1. Field of the Invention
The invention relates to a control device for a vehicle that is provided with a transmission which includes a first engagement mechanism transmitting a torque by meshing and a second engagement mechanism capable of changing a transmission torque capacity.
2. Description of Related Art
Japanese Patent Application Publication No. 2002-174335 (JP 2002-174335 A) discloses a control device for a transmission that is configured to change a torque which is output from an engine and transmit the changed torque to a drive wheel. The transmission is provided with a power transmission path through which the torque is transmitted from an input shaft to an output shaft via a dog clutch and a power transmission path through which the torque is transmitted from the input shaft to the output shaft via a friction clutch. Accordingly, the torque that acts on the dog clutch is gradually reduced as a result of an increase in the transmission torque capacity of the friction clutch, and thus the release of the dog clutch is initiated after the transmission torque capacity of the friction clutch rises to some extent in a case where the dog clutch is released.
The timing when the release of the dog clutch begins can be determined by using the length of time elapsed after the transmission torque capacity of the friction clutch begins to be increased. However, the friction clutch, the dog clutch, or a device that controls these members has inevitable irregularities. Accordingly, the length of time taken to reach a state where the dog clutch can be released after the transmission torque capacity of the friction clutch begins to be increased has inevitable irregularities. Accordingly, the torque continues to act on the dog clutch and the release of the dog clutch cannot be ensured in some cases when the timing of the beginning of the release of the dog clutch is determined based on the length of time after the transmission torque capacity of the friction clutch begins to be increased. Accordingly, the transmission control device that is disclosed in JP 2002-174335 A is configured to detect the transmission torque capacity of the friction clutch and determine whether or not to release the dog clutch based on the detected transmission torque capacity.
In a transmission that is configured to perform switching between a transmission stage which is set by dog clutch engagement and a transmission stage which is set by friction clutch engagement, the torque that acts on the dog clutch can be reduced by increasing the transmission torque capacity of the friction clutch as disclosed in JP 2002-174335 A. Accordingly, no torque acts on the dog clutch when the transmission torque capacity of the friction clutch is increased to a predetermined value. When the transmission torque capacity of the friction clutch is further increased, the torque is transmitted with the meshing of the dog clutch reversed. The torque is transmitted to the dog clutch when the meshing of the dog clutch is reversed by the transmission torque capacity of the friction clutch being increased as described above.